Finfet devices and methods of forming

ABSTRACT

In accordance with some embodiments, a device includes first and second p-type transistors. The first transistor includes a first channel region including a first material of a first fin. The first transistor includes first and second epitaxial source/drain regions each in a respective first recess in the first material and on opposite sides of the first channel region. The first transistor includes a first gate stack on the first channel region. The second transistor includes a second channel region including a second material of a second fin. The second material is a different material from the first material. The second transistor includes third and fourth epitaxial source/drain regions each in a respective second recess in the second material and on opposite sides of the second channel region. The second transistor includes a second gate stack on the second channel region.

This application is a continuation of U.S. patent application Ser. No.15/268,837, entitled “FINFET DEVICES AND METHODS OF FORMING,” filed onSep. 19, 2016 which is a divisional of U.S. patent application Ser. No.14/739,895, entitled “FINFET DEVICES AND METHODS OF FORMING,” filed onJun. 15, 2015 (now U.S. Pat. No. 9,449,975, issued Sep. 20, 2016), whichapplication is hereby incorporated herein by reference.

BACKGROUND

The reduction of the size and the inherent features of semiconductordevices (e.g., field effect transistor (FET) devices) has enabledcontinued improvement in speed, performance, density, and cost per unitfunction of integrated circuits over the past few decades. In accordancewith a design of the FET devices and one of the inherent characteristicsthereof, modulating the length of a channel region underlying a gatebetween a source and drain of a FET device alters a resistanceassociated with the channel region, thereby affecting a performance ofthe FET device. More specifically, shortening the length of the channelregion reduces a source-to-drain resistance of the FET device, which,assuming other parameters are maintained relatively constant, may allowan increase in current flow between the source and drain when asufficient voltage is applied to the gate of the MOS device.

To further enhance the performance of FET devices, stress may beintroduced in the channel region of a FET device to improve carriermobility. Generally, it is desirable to induce a tensile stress in thechannel region of an n-type FET (“NFET”) device in a source-to-draindirection, and to induce a compressive stress in the channel region of ap-type FET (“PFET”) device in a source-to-drain direction.

A commonly used method for applying compressive stress to the channelregions of FET devices includes growing stressors in the source anddrain regions. Such a method typically includes the steps of forming agate stack on a semiconductor substrate, forming gate spacers onsidewalls of the gate stack, forming recesses in the silicon substratealong the gate spacers, and epitaxially growing stressors in therecesses. Since the stressors have a lattice constant different fromthat of silicon, it expands and applies a stress to the channel region,which is located between a source stressor and a drain stressor.

The above-discussed method is affected by pattern-loading effects, whichoccur due to a difference in pattern densities. The pattern-loadingeffects pertain to a phenomenon occurring upon simultaneous etching of asemiconductor substrate in a region of a higher pattern density and aregion of a lower pattern density. The profiles of the trenches arerelated to the density of patterns.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1 through 12 are various three-dimensional (3D) views ofintermediate stages in the manufacturing of fin Field Effect Transistors(finFETs) in accordance with some embodiments

FIGS. 13A, 13B, and 13C are a 3D view and cross-sectional viewsillustrating recessing of source/drain regions in first and secondregions in accordance with some embodiments.

FIGS. 14A, 14B, and 14C are a 3D view and cross-sectional viewsillustrating formation of epitaxial source/drain regions in the recessesformed in FIGS. 13A, 13B, and 13C in accordance with some embodiments.

FIG. 15 is a cross-sectional view of an epitaxial source/drain region ina first region in accordance with some embodiments.

FIG. 16 is a cross-sectional view of an epitaxial source/drain region ina second region in accordance with some embodiments.

FIGS. 17A, 17B, and 17C are a 3D view and cross-sectional viewsillustrating recessing of source/drain regions in third and fourthregions in accordance with some embodiments.

FIGS. 18A, 18B, and 18C are a 3D view and cross-sectional viewsillustrating formation of epitaxial source/drain regions in the recessesformed in FIGS. 17A, 17B, and 17C in accordance with some embodiments.

FIG. 19 is a cross-sectional view of an epitaxial source/drain region ina third region in accordance with some embodiments.

FIG. 20 is a cross-sectional view of an epitaxial source/drain region ina fourth region in accordance with some embodiments.

FIG. 21 is a cross-sectional view of a channel of a fin of a deviceformed in a second or fourth region in accordance with some embodiments.

FIG. 22 is a cross-sectional view of a channel of a fin of a deviceformed in a third region in accordance with some embodiments.

FIG. 23 is a cross-sectional view of a channel of a fin of a deviceformed in a first region in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the invention. Specificexamples of components and arrangements are described below to simplifythe present disclosure. These are, of course, merely examples and arenot intended to be limiting. For example, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed between the first and second features, such thatthe first and second features may not be in direct contact. In addition,the present disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

Fin Field-Effect Transistors (finFETs) and methods of forming the sameare provided in accordance with various embodiments. Intermediate stagesof forming finFETs are illustrated. Some embodiments discussed hereinare discussed in the context of finFETs formed using a gate-lastprocess. Some embodiments contemplate aspects used in a gate-firstprocess. Some variations of the embodiments are discussed. One ofordinary skill in the art will readily understand other modificationsthat may be made that are contemplated within the scope of otherembodiments. Although method embodiments are discussed in a particularorder, various other method embodiments may be performed in any logicalorder and may include fewer or more steps described herein.

FIGS. 1 through 12 are various three-dimensional (3D) views ofintermediate stages in the manufacturing of finFETs in accordance withsome embodiments. In FIG. 1, a substrate 20 is provided. The substrate20 may be a semiconductor substrate, such as a bulk semiconductorsubstrate, a semiconductor-on-insulator (SOI) substrate, a multi-layeredor gradient substrate, or the like. The substrate 20 may include asemiconductor material, such as an elemental semiconductor including Siand Ge; a compound or alloy semiconductor including SiC, SiGe, GaAs,GaP, GaAsP, AlInAs, AlGaAs, GaInAs, InAs, GaInP, InP, InSb, and/orGaInAsP; or a combination thereof. The substrate 20 may be doped orun-doped. In a specific example, the substrate 20 is a bulk siliconsubstrate. The substrate 20 comprises a first region 100, a secondregion 200, a third region 300, and a fourth region 400. Although theregions 100, 200, 300, and 400 are depicted separately, the regions 100,200, 300, and 400 are generally respective portions of a same substrate20, and the specific depictions in the figures are solely for clarity.In the context of the examples provided herein, the first region 100 maybe a core logic n-type device region; the second region 200 may be acore logic p-type device region; the third region 300 may be aninput/output (I/O) p-type device region; and the fourth region 400 maybe a I/O n-type device region.

In FIG. 2, a hardmask 22 is formed on the substrate 20 in the secondregion 200, the third region 300, and the fourth region 400. Thehardmask 22 can be formed by oxidizing, such as a thermal oxidation,chemical oxidation, or the like, a surface of the substrate 20 to formthe hardmask 22 across the first region 100, the second region 200, thethird region 300, and the fourth region 400 and subsequently etching thehardmask 22 in the first region 100 to expose the substrate 20 in thefirst region 100. The etching may use acceptable photolithography andetching techniques. Other materials and methods of forming the hardmask22 may be used.

In FIG. 3, a semiconductor layer 24 is formed on the substrate 20 in thefirst region 100 while the substrate 20 in the second region 200, thethird region 300, and the fourth region 400 remains masked by thehardmask 22. The semiconductor layer 24 can be any semiconductormaterial that is capable of easily oxidizing relative to the material(s)of the substrate 20 and a subsequently formed regrowth layer, as will bediscussed. In some embodiments, the semiconductor layer 24 is agermanium (Ge) containing material, such as SiGe. The semiconductorlayer 24 can be epitaxially grown, such as by Metal-Organic ChemicalVapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), Liquid PhaseEpitaxy (LPE), Vapor Phase Epitaxy (VPE), the like, or a combinationthereof. A thickness of the semiconductor layer 24 can be in a rangefrom about 3 nm to about 15 nm.

In FIG. 4, the hardmask 22 is removed from the second region 200, thethird region 300, and the fourth region 400 of the substrate 20. Theremoval may be by using any appropriate etch, such as an etch selectiveto the material of the hardmask 22. For example, the etch may be a wetetch, such as a diluted HF etch, or the like when the hardmask 22 is anoxide. The etch may be performed in situ after the semiconductor layer24 is formed.

Further in FIG. 4, a regrowth layer 26 is formed on the semiconductorlayer 24 in the first region 100 and on the substrate 20 in the secondregion 200, the third region 300, and the fourth region 400. Theregrowth layer 26 may be a same material as the substrate 20. Forexample, in an embodiment where the substrate 20 is a bulk siliconsubstrate, the regrowth layer 26 may be silicon. The regrowth layer 26can be epitaxially grown, such as by MOCVD, MBE, LPE, VPE, the like, ora combination thereof. A thickness of the regrowth layer 26 can be in arange from about 30 nm to about 60 nm. The regrowth layer 26 may beplanarized, such as by a chemical mechanical polish (CMP).

In FIG. 5, a pad layer 28 and a hardmask layer 30 are formed on theregrowth layer 26. The pad layer 28 can be an oxide formed by oxidizing,such as by a thermal oxidation, chemical oxidation, or the like, asurface of the regrowth layer 26. The hardmask layer 30 can be siliconnitride, silicon carbon nitride, silicon oxynitride, silicon carbonoxynitride, the like, or a combination thereof deposited by chemicalvapor deposition (CVD) or the like. Other materials and methods offorming the pad layer 28 and the hardmask layer 30 may be used.

Further in FIG. 5, the hardmask layer 30 and the pad layer 28 arepatterned and used as masks to form fins 32. The patterning of thehardmask layer 30 and the pad layer 28 may use any acceptablephotolithography and etching process, such as a reactive ion etch (RIE),neutral beam etch (NBE), or the like. Similarly, using the hardmasklayer 30 and the pad layer 28 as masks, the regrowth layer 26, thesemiconductor layer 24, and/or the substrate 20 are etched to form thefins 32. The etching may use any acceptable etching process, such asRIE, NBE, or the like. The etching can form trenches between the fins32. The fins 32 in the first region 100, as illustrated, comprise theregrowth layer 26, the semiconductor layer 24, and the substrate 20. Thefins 32 in the second region 200, as illustrated, comprise the regrowthlayer 26 and the substrate 20. The fins 32 in the third region 300, asillustrated, comprise the regrowth layer 26 and the substrate 20. Thefins 32 in the fourth region 400, as illustrated, comprise the regrowthlayer 26 and the substrate 20.

In FIG. 6, the semiconductor layer 24 in the fins 32 in the first region100 is converted to a first dielectric material 34. In some embodiments,the conversion process is an oxidation process. The oxidation processmay use a steam furnace. For example, the substrate 20 may be placed ina furnace such that the substrate 20 is exposed to a steam environment.As illustrated in FIG. 6, when a steam environment is used foroxidation, the steam may reach the semiconductor layer 24 to convert thesemiconductor layer 24 to the first dielectric material 34. In someembodiments, such as when the semiconductor layer 24 is SiGe, the firstdielectric material 34 may be SiGeO. Other conversion processes may beused. During the conversion process, a second dielectric material 35 maybe formed on the surfaces of the fins 32. For example, the surfaces ofthe fins 32 may also oxidize during an oxidation process.

In FIGS. 7, the trenches are filled with an insulation material 36. Theinsulation material 36 may be an oxide, such as silicon oxide, anitride, the like, or a combination thereof, and may be formed by a highdensity plasma chemical vapor deposition (HDP-CVD), a flowable CVD(FCVD) (e.g., a CVD-based material deposition in a remote plasma systemand post curing to make it convert to another material, such as anoxide), the like, or a combination thereof. Other insulation materialsformed by any acceptable process may be used. In the illustratedembodiment, the insulation material 36 is silicon oxide formed by a FCVDprocess. An anneal process may be performed once the insulation material36 is formed. Further, a planarization process, such as a CMP, mayremove any excess insulation material, the hardmask layer 30, and thepad layer 28, and may form top surfaces of the insulation material 36and top surfaces of the fins 32 that are co-planar.

In FIG. 8, portions of the fins 32 in the second region 200 are removed,and a heteroepitaxial layer 38 is formed as respective portions of thefins 32 in the second region 200. A hardmask layer may be formed in thefirst region 100, the third region 300, and the fourth region 400 whilethe fins 32 in the second region 200 remain exposed. The hardmask layercan be silicon nitride, silicon carbon nitride, silicon oxynitride,silicon carbon oxynitride, the like, or a combination thereof depositedby chemical vapor deposition (CVD) or the like. Other materials andmethods of forming the hardmask layer may be used. The hardmask layermay be patterned to expose the second region 200 using any acceptablephotolithography and etching process, such as RIE, NBE, or the like.With the second region 200 exposed and while the first region 100, thethird region 300, and the fourth region 400 are masked, an etchselective to the material(s) of the fins 32 in the second region 200 isperformed. The etch can be any acceptable etch, such as a dry etch usinga F-based gas, Cl-based gas, or the like. The etch recesses the fins 32in the second region 200.

Then, the heteroepitaxial layer 38 is formed in the recesses. Theheteroepitaxial layer 38 can be epitaxially grown, such as by MOCVD,MBE, LPE, VPE, the like, or a combination thereof. The heteroepitaxiallayer 38 can include any material for an acceptable application of thefinFETs to be formed in the second region 200. In some embodiments, theheteroepitaxial layer 38 is silicon germanium, for example,Si_(x)Ge_(1-x), where x can be in a range from about 0.50 to 0.80, whenthe regrowth layer 26 (if any remains in the second region 200) and/orthe substrate 20 are silicon. A planarization process, such as a CMP,may remove any excess heteroepitaxial layer 38 and the hardmask layer,and may form top surfaces of the heteroepitaxial layer 38 and topsurfaces of the insulation material 36 that are co-planar. A thicknessof the heteroepitaxial layer 38 after the planarization process, ifused, can be in a range from about 30 nm to about 60 nm. The fins 32 inthe second region 200 include the heteroepitaxial layer 38.

Although not specifically illustrated, appropriate wells may be formedin the fins 32 and/or substrate 20. For example, p-wells may be formedin the first region 100 and the fourth region 400 of the substrate 20where n-type devices, such as n-type finFETs, are to be formed, andn-wells may be formed in the second region 200 and the third region 300of the substrate 20 where p-type devices, such as p-type finFETs, are tobe formed.

For example, to form a p-well in the first region 100 and the fourthregion 400, a photoresist can formed over the fins 32 and insulationmaterial 36 in the second region 200 and the third region 300 of thesubstrate 20. The photoresist can be patterned to expose the firstregion 100 and the fourth region 400 of the substrate 20. Thephotoresist can be formed by using a spin-on technique and can bepatterned using acceptable photolithography techniques. Once thephotoresist is patterned, a p-type impurity implant can be performed inthe first region 100 and the fourth region 400, and the photoresist mayact as a mask to substantially prevent p-type impurities from beingimplanted into the second region 200 and the third region 300. Thep-type impurities may be boron, BF₂, or the like implanted in the firstregion 100 and the fourth region 400 to a concentration of equal to orless than about 10¹⁸ cm⁻³, such as between about 10¹⁷ cm⁻³ and about10¹⁸ cm⁻³. After the implant, the photoresist can be removed, such as byan acceptable ashing process.

Further, to form an n-well in the second region 200 and the third region300, a photoresist can be formed over the fins 32 and insulationmaterial 36 in the first region 100 and the fourth region 400 of thesubstrate 20. The photoresist can be patterned to expose the secondregion 200 and the third region 300 of the substrate 20. The photoresistcan be formed by using a spin-on technique and can be patterned usingacceptable photolithography techniques. Once the photoresist ispatterned, an n-type impurity implant may be performed in the secondregion 200 and the third region 300, and the photoresist may act as amask to substantially prevent n-type impurities from being implantedinto the first region 100 and the fourth region 400. The n-typeimpurities may be phosphorus, arsenic, or the like implanted in thesecond region 200 and the third region 300 to a concentration of equalto or less than about 10¹⁸ cm⁻³, such as between about 10¹⁷ cm⁻³ andabout 10¹⁸ cm⁻³. After the implant, the photoresist can be removed, suchas by an acceptable ashing process. After the implants, an anneal may beperformed to activate the p-type and n-type impurities that wereimplanted. The implantations may form a p-well in the first region 100and the fourth region 400 and an n-well in the second region 200 and thethird region 300.

In other embodiments, a p-well and an n-well may be formed in situduring the epitaxial growth of the regrowth layer 26 and/orheteroepitaxial layer 38. The regrowth layer 26 in the different regionswhere different wells are to be formed can be epitaxially grown indifferent growth steps to allow for the different doping types to be inthe different regions.

In FIG. 9, the insulation material 36 is recessed to form isolationregions 40, which may be referred to as Shallow Trench Isolation (STI)regions, and to cause the fins 32 to protrude from between neighboringisolation regions 40. The insulation material 36 may be recessed usingan acceptable etching process, such as one that is selective to thematerial of the insulation material 36. For example, a chemical oxideremoval using a CERTAS® etch or an Applied Materials SICONI tool ordilute hydrofluoric (dHF) acid may be used.

In FIG. 10, a dummy dielectric layer 42 is formed on the fins 32. Thedummy dielectric layer 42 may be, for example, silicon oxide, siliconnitride, a combination thereof, or the like, and may be deposited orthermally grown according to acceptable techniques, such as CVD, thermaloxidation, or the like.

In FIG. 11, a dummy gate layer is formed over the dummy dielectric layer42. The dummy gate layer may be deposited, such as by using CVD or thelike, over the dummy dielectric layer 42 and then planarized, such as bya CMP. The dummy gate layer may comprise, for example, polysilicon,although other materials that have a high etching selectivity may alsobe used. A mask layer is then formed over the dummy gate layer. The masklayer may be deposited, such as by using CVD or the like, over the dummygate layer. The mask layer may comprise, for example, silicon nitride,silicon oxynitride, silicon carbon nitride, or the like.

Further in FIG. 11, the mask layer is patterned using acceptablephotolithography and etching techniques to form a mask 46. Further, thedummy gate layer and dummy dielectric layer 42 are patterned, such as bytransferring the pattern of the mask 46, by using an acceptable etchingtechnique to form dummy gates 44 and dummy gate dielectrics from thedummy gate layer and the dummy dielectric layer 42, respectively. Theetching may comprise an acceptable anisotropic etching, such as RIE,NBE, or the like. The dummy gates 44 cover respective channel regions ofthe fins 32. The dummy gates 44 may also have a lengthwise directionsubstantially perpendicular to the lengthwise direction of therespective fins 32.

Although not specifically illustrated, implants for lightly dopedsource/drain (LDD) regions may be performed. Similar to the implantsdiscussed above, a mask, such as a photoresist, may be formed over thesecond region 200 and the third region 300, e.g., for p-type devices,while exposing the first region 100 and the fourth region 400, e.g., forn-type devices, and n-type impurities may be implanted into the exposedfins 32 in the first region 100 and the fourth region 400. The mask maythen be removed. Subsequently, a mask, such as a photoresist, may beformed over the first region 100 and the fourth region 400 whileexposing the second region 200 and the third region 300, and p-typeimpurities may be implanted into the exposed fins 32 in the secondregion 200 and the third region 300. The mask may then be removed. Then-type impurities may be the any of the n-type impurities previouslydiscussed, and the p-type impurities may be the any of the p-typeimpurities previously discussed. The lightly doped source/drain regionsmay have a concentration of impurities from about 10¹⁵ cm⁻³ to about10¹⁶ cm⁻³. An anneal may be used to activate the implanted impurities.

Further in FIG. 11, gate spacers 48 are formed along sidewalls of thedummy gate dielectric, dummy gate 44, and mask 46. The gate spacers 48may be formed by conformally depositing, such as by CVD or the like, amaterial and subsequently anisotropically etching the material. Thematerial of the gate spacers 48 may be silicon nitride, silicon carbonnitride, a combination thereof, or the like.

Further in FIG. 11, epitaxial source/drain regions 50 and 52 are formedin the fins 32. A hardmask layer may be formed in the second region 200and the third region 300 while the fins 32 in the first region 100 andthe fourth region 400 remain exposed. The hardmask layer can be siliconnitride, silicon carbon nitride, silicon oxynitride, silicon carbonoxynitride, the like, or a combination thereof deposited by CVD or thelike. Other materials and methods of forming the hardmask layer may beused. The hardmask layer may be patterned to expose the first region 100and the fourth region 400 using any acceptable photolithography andetching process, such as RIE, NBE, or the like. With the first region100 and the fourth region 400 exposed and the second region 200 and thethird region 300 masked, an etch selective to the material(s) of thefins 32 in the first region 100 and the fourth region 400 is performed.The etch can be any acceptable etch, such as a dry or wet etch, whichmay be anisotropic or isotropic. In some embodiments, the etch caninclude a dry etch using a F-based gas, Cl-based gas, or the like. Theetch recesses source/drain regions of the fins 32 in the first region100 and the fourth region 400. Additional details of the recesses formedin the source/drain regions of the fins 32 in the first region 100 andthe fourth region 400 are discussed below in the context of FIGS. 17A-C,18A-C, 19, and 20.

The epitaxial source/drain regions 50 are then epitaxially grown in therecesses in the first region 100 and the fourth region 400. Theepitaxial growth may be by using MOCVD, MBE, LPE, VPE, the like, or acombination thereof. The epitaxial source/drain regions 50 may compriseany acceptable material, such as appropriate for the device type, e.g.,n-type. For example, the epitaxial source/drain regions 50 for an n-typedevice may comprise silicon, SiP, SiC, SiCP, the like, or a combinationthereof. Additional details of an example of the epitaxial source/drainregions 50 in the first region 100 and the fourth region 400 arediscussed below in the context of FIGS. 18A-C, 19, and 20. Then, thehardmask layer may be removed from the second region 200 and the thirdregion 300, for example, using an etch selective to the material of thehardmask layer.

Another hardmask layer may be formed in the first region 100 and thefourth region 400 while the fins 32 in the second region 200 and thethird region 300 remain exposed. The hardmask layer can be siliconnitride, silicon carbon nitride, silicon oxynitride, silicon carbonoxynitride, the like, or a combination thereof deposited by CVD or thelike. Other materials and methods of forming the hardmask layer may beused. The hardmask layer may be patterned to expose the second region200 and the third region 300 using any acceptable photolithography andetching process, such as RIE, NBE, or the like. With the second region200 and the third region 300 exposed and the first region 100 and thefourth region 400 masked, an etch selective to the material(s) of thefins 32 in the second region 200 and the third region 300 is performed.The etch can be any acceptable etch, such as a dry or wet etch, whichmay be anisotropic or isotropic. In some embodiments, the etch caninclude a dry etch using a F-based gas, Cl-based gas, or the like. Theetch recesses source/drain regions of the fins 32 in the second region200 and the third region 300. Additional details of the recesses formedin the source/drain regions of the fins 32 in the second region 200 andthe third region 300 are discussed below in the context of FIGS. 13A-C,14A-C, 15, and 16.

The epitaxial source/drain regions 52 are then epitaxially grown in therecesses in the second region 200 and the third region 300. Theepitaxial growth may be by using MOCVD, MBE, LPE, VPE, the like, or acombination thereof. The epitaxial source/drain regions 52 may compriseany acceptable material, such as appropriate for the device type, e.g.,p-type. For example, the epitaxial source/drain regions 52 for a p-typedevice may comprise SiGe, SiGeB, Ge, GeSn, or the like. Additionaldetails of an example of the epitaxial source/drain regions 52 in thesecond region 200 and the third region 300 are discussed below in thecontext of FIGS. 14A-C, 15, and 16. Then, the hardmask layer may beremoved from the first region 100 and the fourth region 400, forexample, using an etch selective to the material of the hardmask layer.

In FIG. 12, a bottom inter-layer dielectric (ILDO) 54 is formed over thefins 32. The ILDO 54 can comprise a first layer, such as an etch stoplayer (ESL), conformally formed on the epitaxial source/drain regions 50and 52, the gate spacers 48, the masks 46, and the isolation regions 40.In some embodiments, the ESL may comprise silicon nitride, siliconcarbonitride, or the like, formed using Atomic Layer Deposition (ALD),CVD, the like, or a combination thereof. The ILDO 54 can furthercomprise a second layer deposited over the first layer. The second layerof the ILDO 54 may comprise Phospho-Silicate Glass (PSG), Boro-SilicateGlass (BSG), Boron-Doped Phospho-Silicate Glass (BPSG), undoped SilicateGlass (USG), or the like, and may be deposited by any suitable method,such as CVD, plasma-enhanced CVD (PECVD), FCVD, the like, or acombination thereof.

A planarization process, such as a CMP, is performed to level the topsurface of ILDO 54 with the top surfaces of the dummy gates 44. The CMPmay also remove the masks 46 from over the dummy gates 44. Accordingly,top surfaces of the dummy gates 44 are exposed through the ILDO 54.

Then, the dummy gates 44 and the dummy gate dielectric are removed in anetching step(s), so that openings through the ILDO 54 and defined by thegate spacers 48 are formed to the respective fins 32. The openingsexpose respective channel regions of the fins 32. Each channel region isdisposed between a neighboring pair of epitaxial source/drain regions 50or 52. The etching step(s) may be selective to the materials of thedummy gates 44 and the dummy gate dielectric, which etching may be a dryor wet etching. During the etching, the dummy gate dielectric may beused as an etch stop layer when the dummy gates 44 are etched. The dummygate dielectric may then be etched after the removal of the dummy gates44.

In FIG. 12, a gate dielectric and a gate electrode (collectively “gatestack 56”) are formed in the opening through the ILDO 54. An interfacialdielectric can be formed in each opening and on the respective fins 32.The interfacial dielectric may be, for example, an oxide or the like. Asan example, a first interfacial layer can be formed in the openings andon the fins 32 in the first region 100, the second region 200, the thirdregion 300, and the fourth region 400. The first interfacial layer canbe formed using, for example, an ALD oxide deposition conformal to thestructures in the regions 100, 200, 300, and 400. Subsequently, aphotoresist can be formed in the third region 300 and the fourth region400 while the first region 100 and the second region remain exposed. Thephotoresist can be formed by using a spin-on technique and can bepatterned using acceptable photolithography techniques. Once thephotoresist is patterned, an etch selective to the material of the firstinterfacial dielectric layer can be performed to remove the firstinterfacial dielectric layer from the first region 100 and the secondregion 200. Then, a second interfacial layer can be formed on the fins32 exposed by the openings in the first region 100 and the second region200 using, for example, a chemical oxidation to form an oxide. Thechemical oxidation can include exposing the fins 32 to a chemicaloxidant, such as ozone, water, hydrogen peroxide, or the like. Hence,embodiments contemplate different interfacial layers being formed in thefirst region 100 and second region 200 from what is formed in the thirdregion 300 and the fourth region 400. Additional details of theseinterfacial layers are discussed below in the context of FIGS. 21, 22,and 23.

A gate dielectric layer can be formed on the interfacial layers. Thegate dielectric layer can further include a high-k dielectric layerformed conformally on the top surface of the ILDO 54 and in the openingsalong sidewalls of the gate spacers 48 and on the interfacialdielectric. The high-k dielectric layer may have a k value greater thanabout 7.0, and may include a metal oxide or a silicate of Hf, Al, Zr,La, Mg, Ba, Ti, Pb, and combinations thereof. The formation methods ofhigh-k dielectric layer may include ALD, CVD, Molecular-Beam Deposition(MBD), the like, or a combination thereof. Other embodiments contemplateother materials for the gate dielectric, such as materials that are nothigh-k.

The gate electrode is formed on the gate dielectric. The gate electrodecan be a multi-layered structure. For example, the gate electrode caninclude a capping layer conformally formed on the gate dielectric, oneor more work function tuning layers conformally formed on the cappinglayer, and a metal-containing material, such as a metal, formed on thework function tuning layers and filling the openings. In an example, thecapping layer can comprise a first sub-layer on the gate dielectricformed of TiN or the like using ALD, CVD, or the like, and a secondsub-layer on the first sub-layer formed of TaN or the like using ALD,CVD, or the like. The work function tuning layer(s) can be formed ofTiAl, TiN, or the like using ALD, CVD, or the like. The metal-containingmaterial can be tungsten (W), aluminum (Al), cobalt (Co), ruthenium(Ru), a combination thereof or the like deposited using CVD, physicalvapor deposition (PVD), the like, or a combination thereof.

Next, a planarization process, such as a CMP, may be performed to removethe excess portions of the gate electrodes and the gate dielectrics,which excess portions are over the top surface of ILD0 54.

Although not depicted, an upper ILD (ILD1) can be deposited over theILD0 54 and the gate stack 56, and contacts can then be formed throughthe ILD1 and ILD0 54 to the epitaxial source/drain regions 50 and 52.The ILD1 can be formed of a dielectric material such as PSG, BSG, BPSG,USG, or the like, and may be deposited by any suitable method, such asCVD and PECVD. Openings for contacts can be formed through the ILD1 andILD0 54. The openings may be formed using acceptable photolithographyand etching techniques. A liner, such as a diffusion barrier layer, anadhesion layer, or the like, and a conductive material can be formed inthe openings. The liner may include titanium, titanium nitride,tantalum, tantalum nitride, or the like. The conductive material may becopper, a copper alloy, silver, gold, tungsten, aluminum, nickel, or thelike. A planarization process, such as a CMP, may be performed to removeexcess material from a surface of the ILD1. The remaining liner andconductive material can form contacts in the openings. An anneal processmay be performed to form a silicide at the interface between theepitaxial source/drain regions 50 and 52 and the contacts. Furtherprocessing steps may be performed. For example, various Inter-MetalDielectrics (IMD) and their corresponding metallizations may be formedover the ILD1.

FIGS. 13A, 13B, and 13C illustrate the recessing of the source/drainregions in the second region 200 and the third region 300 discussedabove with respect to FIG. 11. FIG. 13A is a 3D view of the secondregion 200 and the third region 300 on the substrate 20. FIG. 13B is across-sectional view of the second region 200, which is also thecross-section B-B in FIG. 13A. FIG. 13C is a cross-sectional view of thethird region 300, which is also the cross-section C-C in FIG. 13A. Therecessing of the fins 32 in both the second region 200 and the thirdregion 300 is performed in a same etch process. An etchant used in thisetch process can etch the material of the heteroepitaxial layer 38 at afaster rate, including rates of anisotropic etching and isotropicetching, than the material of the regrowth layer 26. An example etchprocess includes using a dry etch using a F-based gas, Cl-based gas, orthe like when the heteroepitaxial layer 38 is SiGe and the regrowthlayer 26 is silicon.

As shown, a nearest distance 60 between outer surfaces of gate spacers48 on neighboring stacks of a dummy dielectric, dummy gate 44, and mask46 (collectively, “dummy stack 44/46”) in the second region 200 issmaller than a nearest distance 62 between outer surfaces of gatespacers 48 on neighboring dummy stacks 44/46 in the third region 300.The different etch rates of the materials of the heteroepitaxial layer38 and the regrowth layer 26 can offset the pattern-loading effect thatcan occur during etching, such as when distance 62 is greater thandistance 60. As will be discussed in further detail with respect toFIGS. 15 and 16, a depth 64 of recesses formed in the second region 200can be greater than a depth 66 of recesses formed in the third region300.

FIGS. 14A, 14B, and 14C illustrate the epitaxial growth of the epitaxialsource/drain regions 52′ and 52″ (collectively, 52) in the recesses inthe second region 200 and the third region 300, respectively, discussedabove with respect to FIG. 11. FIG. 14A is a 3D view of the secondregion 200 and the third region 300 on the substrate 20. FIG. 14B is across-sectional view of the second region 200, which is also thecross-section B-B in FIG. 14A. FIG. 14C is a cross-sectional view of thethird region 300, which is also the cross-section C-C in FIG. 14A. Theepitaxial growth of the epitaxial source/drain regions 52 in both thesecond region 200 and the third region 300 is performed in a same growthprocess. As will be discussed further in FIGS. 15 and 16, the epitaxialsource/drain regions 52′ in the second region 200 in FIG. 14B and theepitaxial source/drain regions 52″ in the third region 300 in FIG. 14Ccan fill the respective recesses.

FIG. 15 illustrates a cross-sectional view of an epitaxial source/drainregion 52′, which includes a first portion 52 a′ and a second portion 52b′, in the second region 200. As illustrated, the first portion 52 a′ ofthe epitaxial source/drain region 52′ fills the recess, which was formedas discussed with respect to FIGS. 13A and 13B. The first portion 52 a′may be, for example, Si_(x)Ge_(1-x), where x can be in a range fromabout 0.30 to 0.70, that is boron doped at a concentration in a rangefrom about 7×10²⁰ cm⁻³ to about 2×10²¹ cm⁻³. The second portion 52 b′may be, for example, Si_(x)Ge_(1-x), where x can be in a range fromabout 0.00 to 0.40, that is boron doped at a concentration in a rangefrom about 5×10²⁰ cm⁻³ to about 2×10²¹ cm⁻³.

The epitaxial source/drain region 52′ (e.g., the first portion 52 a′) inthe second region 200 can have a proximity distance 68. The proximitydistance 68 is a lateral distance between an outer surface of theepitaxial source/drain region 52′ and a plane of a nearest sidewallsurface of the nearest dummy stack 44/46. In some embodiments, theproximity distance 68 can be in a range from about 0 nm to about 8 nm.The first portion 52 a′ can have a thickness 70 from a bottom surface toa top surface. In some embodiments, the thickness 70 can be in a rangefrom about 20 nm to about 40 nm. The second portion 52 b′ can have athickness 72 from a bottom surface to a top surface. In someembodiments, the thickness 72 can be in a range from about 5 nm to about10 nm. A distance 74 can be between opposing sidewalls of neighboringdummy stacks 44/46, which can also be the distance 60 plus two times athickness of the gate spacers 48. In some embodiments, the distance 74can be in a range from about 15 nm to about 36 nm. The epitaxialsource/drain region 52′ can have a raised height 76 from a top surfaceof the fin 32 (e.g., top surface of the heteroepitaxial layer 38) to atop surface of the epitaxial source/drain region 52′ (e.g., the secondportion 52 b′). In some embodiments, the raised height 76 can be in arange from about 5 nm to about 10 nm.

FIG. 16 illustrates a cross-sectional view of an epitaxial source/drainregion 52″, which includes a first portion 52 a″ and a second portion 52b″, in the third region 300. As illustrated, the first portion 52 a″ ofthe epitaxial source/drain region 52″ fills the recess, which was formedas discussed with respect to FIGS. 13A and 13C. The first portion 52 a″may be, for example, Si_(x)Ge_(1-x), where x can be in a range fromabout 0.30 to 0.70, that is boron doped at a concentration in a rangefrom about 7×10²⁰ cm⁻³ to about 2×10²¹ cm⁻³. The second portion 52 b″may be, for example, Si_(x)Ge_(1-x), where x can be in a range fromabout 0.00 to 0.40, that is boron doped at a concentration in a rangefrom about 5×10²⁰ cm⁻³ to about 2 ×10²¹ cm⁻³. The first portion 52 a″ inthe epitaxial source/drain region 52″ in the third region 300 can beepitaxially grown simultaneously with the first portion 52 a′ in theepitaxial source/drain region 52′ in the second region 200. The secondportion 52 b″ in the epitaxial source/drain region 52″ in the thirdregion 300 can be epitaxially grown simultaneously with the secondportion 52 b′ in the epitaxial source/drain region 52′ in the secondregion 200.

The epitaxial source/drain region 52″ (e.g., the first portion 52 a″) inthe third region 300 can have a proximity distance 78. The proximitydistance 78 is a lateral distance between an outer surface of theepitaxial source/drain region 52″ and a plane of a nearest sidewallsurface of the nearest dummy stack 44/46. In some embodiments, theproximity distance 78 can be in a range from about 4 nm to about 15 nm.The first portion 52 a″ can have a thickness 80 from a bottom surface toa top surface. In some embodiments, the thickness 80 can be in a rangefrom about 20 nm to about 40 nm. The second portion 52 b″ can have athickness 82 from a bottom surface to a top surface. In someembodiments, the thickness 82 can be in a range from about 5 nm to about10 nm. A distance 84 can be between opposing sidewalls of neighboringdummy stacks 44/46, which can also be the distance 62 plus two times athickness of the gate spacers 48. In some embodiments, the distance 84can be in a range from about 40 nm to about 100 nm. The epitaxialsource/drain region 52″ can have a raised height 86 from a top surfaceof the fin 32 (e.g., top surface of the regrowth layer 26) to a topsurface of the epitaxial source/drain region 52″ (e.g., the secondportion 52 b″). In some embodiments, the raised height 86 can be in arange from about 5 nm to about 10 nm.

The different etch rates during etching of the recesses for theepitaxial source/drain regions 52′ and 52″ in the second region 200 andthe third region 300, respectively, can cause profiles of the epitaxialsource/drain regions 52′ and 52″ to be different. For example, the depth64 of the recesses in the second region 200 can be greater than thedepth 66 of the recesses in the third region 300, even though distance60 in the second region 200 is less than distance 62 in the thirdregion. Similarly, an isotropic etch component of the etch can under-cutthe gate spacers 48 more significantly in the second region 200 than thethird region 300, such as due to the greater etch rate in the secondregion 200. This can result in the source/drain region 52″ in the thirdregion 300 having a greater proximity distance 78 than the proximitydistance 68 of the source/drain region 52′ in the second region 200. Insome embodiments, the proximity distance 78 is in a range from about 2nm to about 8 nm greater than the proximity distance 68.

FIGS. 17A, 17B, and 17C illustrate the recessing of the source/drainregions in the first region 100 and the fourth region 400 discussedabove with respect to FIG. 11. FIG. 17A is a 3D view of the first region100 and the fourth region 400 on the substrate 20. FIG. 17B is across-sectional view of the first region 100, which is also thecross-section B-B in FIG. 17A. FIG. 17C is a cross-sectional view of thefourth region 400, which is also the cross-section C-C in FIG. 17A. Therecessing of the fins 32 in both the first region 100 and the fourthregion 400 is performed in a same etch process. An example etch processincludes using a dry etch using a F-based gas, Cl-based gas, or the likewhen the regrowth layer 26 is silicon.

As shown, a nearest distance 88 between outer surfaces of gate spacers48 on neighboring dummy stacks 44/46 in the first region 100 is smallerthan a nearest distance 90 between outer surfaces of gate spacers 48 onneighboring dummy stacks 44/46 in the fourth region 400. Due to thepattern-loading effect and the same material being etched, e.g., theregrowth layers 26, in the first region 100 and the fourth region 400,the regrowth layer 26 in the fourth region 400 can be etched at a fasterrate than the regrowth layer 26 in the first region 100. As will bediscussed in further detail with respect to FIGS. 19 and 20, a depth 92of recesses formed in the first region 100 can be less than a depth 94of recesses formed in the fourth region 400.

FIGS. 18A, 18B, and 18C illustrate the epitaxial growth of the epitaxialsource/drain regions 50′ and 50″ (collectively, 50) in the recesses inthe first region 100 and the fourth region 400 discussed above withrespect to FIG. 11. FIG. 18A is a 3D view of the first region 100 andthe fourth region 400 on the substrate 20. FIG. 18B is a cross-sectionalview of the first region 100, which is also the cross-section B-B inFIG. 18A. FIG. 18C is a cross-sectional view of the fourth region 400,which is also the cross-section C-C in FIG. 18A. The epitaxial growth ofthe epitaxial source/drain regions 50 in both the first region 100 andthe fourth region 400 is performed in a same growth process(es). As willbe discussed further in FIGS. 19 and 20, the epitaxial source/drainregions 50′ in the first region 100 in FIG. 18B can fill the recesses,while the epitaxial source/drain regions 50″ in the fourth region 400 inFIG. 14C may not completely fill the recesses.

FIG. 19 illustrates a cross-sectional view of an epitaxial source/drainregion 50′, which includes first portions 50 a′, second portions 50 b′,and a third portion 50 c′, in the first region 100. As illustrated, thefirst portions 50 a′ of the epitaxial source/drain region 50′ are formedon surfaces of a crystalline material, such as the regrowth layer 26 andthe substrate 20, and not on a surface of non-crystalline material, suchas the first dielectric material 34. Hence, FIG. 19 illustrates threedistinct first portions 50 a′ along surfaces of the recess in the firstregion 100. The second portions 50 b′ of the epitaxial source/drainregion 50′ are formed on the first portions 50 a′, e.g., on surfaces ofa crystalline material and not on surfaces of a non-crystallinematerial. The third portion 50 c′ of the epitaxial source/drain region50′ fills the remainder of the recess in the first region 100. Althoughthe third portion 50 c′ may not nucleate and grow from surfaces ofnon-crystalline material such as the first dielectric material 34,growth fronts of the third portion 50 c′ can grow from neighboringsurfaces of crystalline material and coalesce on a surface ofnon-crystalline material. The first portions 50 a′ may be, for example,Si that is undoped. The second portions 50 b′ may be, for example, SiPthat is phosphorus doped at a concentration in a range from about 2×10²⁰cm⁻³ to about 8×10²⁰ cm⁻³. The third portion 50 c′ may be, for example,SiP that is phosphorus doped at a concentration in a range from about1×10²¹ cm⁻³ to about 3×10²¹ cm⁻³.

The epitaxial source/drain region 50′ (e.g., first portions 50 a′) inthe first region 100 can have a proximity distance 96. The proximitydistance 96 is a lateral distance between an outer surface of theepitaxial source/drain region 50′ and a plane of a nearest sidewallsurface of the nearest dummy stack 44/46. In some embodiments, theproximity distance 96 can be in a range from about 2 nm to about 8 nm.The first portions 50 a′ can have a thickness 98. In some embodiments,the thickness 98 can be in a range from about 5 nm to about 30 nm. Thesecond portions 50 b′ can have a thickness 102. In some embodiments, thethickness 102 can be in a range from about 5 nm to about 10 nm. Thethird portion 50 c′ can have a thickness 104. In some embodiments, thethickness 104 can be in a range from about 20 nm to about 50 nm. Adistance 106 can be between opposing sidewalls of neighboring dummystacks 44/46, which can also be the distance 88 plus two times athickness of the gate spacers 48. In some embodiments, the distance 106can be in a range from about 15 nm to about 36 nm. The epitaxialsource/drain region 50′ can have a raised height 108 from a top surfaceof the fin 32 (e.g., top surface of the regrowth layer 26) to a topsurface of the epitaxial source/drain region 50′ (e.g., the thirdportion 50 c′). In some embodiments, the raised height 108 can be in arange from about 5 nm to about 10 nm. The first dielectric material 34can have a thickness 110. In some embodiments, the thickness 110 can bein a range from about 5 nm to about 25 nm.

FIG. 20 illustrates a cross-sectional view of an epitaxial source/drainregion 50″, which includes a first portion 50 a″, a second portion 50b″, and a third portion 50 c″, in the fourth region 400. As illustrated,the first portion 50 a″ of the epitaxial source/drain region 50″ is aconformal layer along surfaces of a crystalline material (e.g., theregrowth layer 26 and/or the substrate 20) in the recess, which wasformed as discussed with respect to FIGS. 17A and 17C. As illustrated,the second portion 50 b″ of the epitaxial source/drain region 50″ is aconformal layer along surfaces of the first portion 50 a″. The thirdportion 50 c″ of the epitaxial source/drain region 50″ is on the secondportion 50 b″ and in some embodiments may not completely fill theremaining portion of the recess. The first portion 50 a″ may be, forexample, Si that is undoped. The second portion 50 b″ may be, forexample, SiP that is phosphorus doped at a concentration in a range fromabout 2×10²⁰ cm⁻³ to about 8×10²⁰ cm⁻³. The third portion 50 c″ may be,for example, SiP that is phosphorus doped at a concentration in a rangefrom about 1×10²¹ cm⁻³ to about 3×10²¹ cm⁻³. The first portion 50 a″ inthe epitaxial source/drain region 50″ in the fourth region 400 can beepitaxially grown simultaneously with the first portions 50 a′ in theepitaxial source/drain region 50′ in the first region 100. The secondportion 50 b″ in the epitaxial source/drain region 50″ in the fourthregion 400 can be epitaxially grown simultaneously with the secondportions 50 b′ in the epitaxial source/drain region 50′ in the firstregion 100. The third portion 50 c″ in the epitaxial source/drain region50″ in the fourth region 400 can be epitaxially grown simultaneouslywith the third portion 50 c′ in the epitaxial source/drain region 50′ inthe first region 100.

The epitaxial source/drain region 50″ (e.g., the first portion 50 a″) inthe fourth region 400 can have a proximity distance 112. The proximitydistance 112 is a lateral distance between an outer surface of theepitaxial source/drain region 50″ and a plane of a nearest sidewallsurface of the nearest dummy stack 44/46. In some embodiments, theproximity distance 112 can be in a range from about 2 nm to about 8 nm.The first portion 50 a″ can have a thickness 114. In some embodiments,the thickness 114 can be in a range from about 5 nm to about 30 nm. Thesecond portion 50 b″ can have a thickness 116. In some embodiments, thethickness 116 can be in a range from about 5 nm to about 10 nm. Thethird portion 50 c″ can have a thickness 118. In some embodiments, thethickness 118 can be in a range from about 20 nm to about 50 nm. Adistance 120 can be between opposing sidewalls of neighboring dummystacks 44/46, which can also be the distance 90 plus two times athickness of the gate spacers 48. In some embodiments, the distance 120can be in a range from about 40 nm to about 100 nm. The epitaxialsource/drain region 50″ can be dished by, for example, a dimension 122from a top surface of the fin 32 (e.g., top surface of the regrowthlayer 26) to a top surface of the epitaxial source/drain region 50″(e.g., the third portion 50 c″). In some embodiments, the dimension 122can be in a range from about 5 nm to about 20 nm.

Due to the pattern-loading effect when etching the same materials of theregrowth layer 26 to form recesses for the epitaxial source/drainregions 50′ and 50″ in the first region 100 and the fourth region 400,respectively, profiles of the epitaxial source/drain regions 50′ and 50″can be different. For example, the pattern-loading effect may cause ananisotropic component of the etching, which may be the dominant etchingcomponent, to etch at a faster rate in the fourth region 400 than thefirst region 100 because the distance 90 is greater than the distance88. Hence, the depth 94 of the recess in the fourth region 400 may begreater than the depth 92 of the recess in the first region 100. Forexample, in some embodiments, the depth 94 of the recess in the fourthregion 400 is in a range from about 3 nm to about 15 nm greater than thedepth 92 of the recess in the first region 100. Further, the isotropicetching component may have a same or similar etching rate in the firstregion 100 and the fourth region 400. Hence, lateral under-cutting ofthe recessing under the dummy stacks 44/46 in the first region 100 andthe fourth region 400 may be the same or similar, and the proximitydistances 96 and 112 in the first region 100 and the fourth region 400may be the same or similar.

Although the foregoing discussion references dummy stacks 44/46 in thecontext of certain dimensions, one having ordinary skill in the art willunderstand that such dimensions remain in the context of gate stacks 56in the stead of dummy stacks 44/46 after the gate stacks 56 are formedin openings defined by the removal of dummy stacks 44/46. For example, aproximity distance may be a lateral distance between an outer surface ofan epitaxial source/drain region 50 or 52 and a plane of a nearestsidewall surface of the nearest gate stack 56 (e.g., an outer sidewallsurface of a conformal interfacial or gate dielectric layer).

FIGS. 21, 22, and 23 illustrate cross-sectional views of fins at channelregions of the devices that are formed in the regions 100, 200, 300, and400. The devices are illustrated after forming gate stacks 56 asdiscussed above with respect to FIG. 12. For clarity, thecross-sectional views of FIGS. 21, 22, and 23 are perpendicular to thecross-sections B-B and C-C illustrated in FIGS. 14A and 18A.

FIG. 21 illustrates a cross-sectional view of a channel of a fin 32 of adevice formed in the third region 300 and/or a channel of a fin of adevice formed in the fourth region 400. FIG. 21 illustrates the fin 32,including the regrowth layer 26, protruding from above neighboringisolation regions 40. A gate stack 56 is on and over the fin 32 andincludes an interfacial layer 130, a gate dielectric layer 132, and agate electrode 134. The gate stack 56 can be formed as discussed abovewith respect to FIG. 12. In some embodiments, a thickness of theinterfacial layer 130 can be in a range from about 2 nm to about 5 nm.The fin 32 can have a fin height 136 protruding above the isolationregions 40. The fin height 136 can be in a range from about 30 nm toabout 60 nm in some embodiments. The fin 32 can have a fin width 138from one sidewall surface to another sidewall surface. In someembodiments, the fin width 138 can be in a range from about 4 nm toabout 10 nm.

FIG. 22 illustrates a cross-sectional view of a channel of a fin 32 of adevice formed in the first region 100. FIG. 22 illustrates the fin 32,including the first dielectric material 34 and the regrowth layer 26,protruding from above neighboring isolation regions 40. A gate stack 56is on and over the fin 32 and includes an interfacial layer 140, a gatedielectric layer 142, and a gate electrode 144. The gate stack 56 can beformed as discussed above with respect to FIG. 12. In some embodiments,a thickness of the interfacial layer 140 can be in a range from about 5nm to about 15 nm. The fin 32, e.g., the regrowth layer 26 in thisexample, can have a fin height 146 protruding above the isolationregions 40 and above the first dielectric material 34. The fin height146 can be in a range from about 30 nm to about 60 nm in someembodiments. In some embodiments, the first dielectric material 34 canbe completely above or completely below top surfaces of the isolationregions 40. The fin 32, e.g., the regrowth layer 26 in this example, canhave a fin width 148 from one sidewall surface to another sidewallsurface. In some embodiments, the fin width 148 can be in a range fromabout 4 nm to about 10 nm.

FIG. 23 illustrates a cross-sectional view of a channel of a fin 32 of adevice formed in the second region 200. FIG. 23 illustrates the fin 32,including the heteroepitaxial layer 38, protruding from aboveneighboring isolation regions 40. A gate stack 56 is on and over the fin32 and includes an interfacial layer 150, a gate dielectric layer 152,and a gate electrode 154. The gate stack 56 can be formed as discussedabove with respect to FIG. 12. In some embodiments, a thickness of theinterfacial layer 150 can be in a range from about 5 nm to about 15 nm.The fin 32, e.g., the heteroepitaxial layer 38 in this example, can havea fin height 156 protruding above the isolation regions 40 and above aninterface between the heteroepitaxial layer 38 and an underlyingmaterial. The fin height 156 can be in a range from about 30 nm to about60 nm in some embodiments. In some embodiments, the heteroepitaxiallayer 38 can be completely above top surfaces of the isolation regions40 or can extend partially below the top surface of the isolationregions 40. The fin 32, e.g., the heteroepitaxial layer 38 in thisexample, can have a fin width 158 from one sidewall surface to anothersidewall surface. In some embodiments, the fin width 158 can be in arange from about 4 nm to about 10 nm.

Some embodiments can achieve advantages. By having a different materialas in channel regions of fins in different regions (e.g., second region200 and third region 300), recess profiles can be manipulated when asimultaneous etching is performed for source/drain regions, which mayoffset a pattern-loading effect. This can advantageously result indifferent proximity distances in those different regions. The differentproximity distances can result in increased reliability in an integratedcircuit. For example, when the third region 300 is an I/O p-type deviceregion and the second region 200 is a core logic p-type device region, ahigher VDD may be used for an I/O p-type device in the third region 300compared to a core logic p-type device in the second region, and hence,an increased proximity distance may be advantageous in the third region300 compared to the second region 200. Some embodiments, such asdescribed above, can be easily and simply integrated into process flows,and can be cost effective.

An embodiment is a device. The device includes a first p-type transistorand a second p-type transistor. The first p-type transistor includes afirst channel region including a first material of a first fin on asubstrate. The first p-type transistor includes a first epitaxialsource/drain region and a second epitaxial source/drain region each in arespective first recess in the first material. The first channel regionis disposed between the first epitaxial source/drain region and thesecond epitaxial source/drain region. The first p-type transistorincludes a first gate stack on the first channel region. The secondp-type transistor includes a second channel region including a secondmaterial of a second fin on the substrate. The second material is adifferent material from the first material. The second p-type transistorincludes a third epitaxial source/drain region and a fourth epitaxialsource/drain region each in a respective second recess in the secondmaterial. The second channel region is disposed between the thirdepitaxial source/drain region and the fourth epitaxial source/drainregion. The second p-type transistor includes a second gate stack on thesecond channel region.

Another embodiment is a method. The method comprises forming a first finon a substrate, the first fin comprising a first crystalline material onthe substrate; forming a second fin on the substrate, the second fincomprising a second crystalline material on the substrate, a material ofthe first crystalline material being different from a material of thesecond crystalline material; forming a first structure on the firstcrystalline material of the first fin and a second structure on thesecond crystalline material of the second fin; forming a first spaceralong a sidewall of the first structure and a second spacer along asidewall of the second structure; simultaneously etching the firstcrystalline material to form a first recess in the first fin andadjacent the first spacer, and etching the second crystalline materialto form a second recess in the second fin and adjacent the secondspacer, the first recess extending laterally under the first spacerfurther than the second recess laterally extends under the secondspacer; and epitaxially growing a first epitaxial source/drain region inthe first recess and a second source/drain region in the second recess.

A further embodiment is a method. The method comprises forming a firstfin in a p-type core logic region of a substrate, the first fincomprising a SiGe channel layer; forming a second fin in a p-typeinput/output (I/O) region of the substrate, the second fin comprising afirst silicon channel layer; forming a first stack and a second stack onthe first fin, and a third stack and a fourth stack on the second fin;forming a first spacer on a sidewall of the first stack, a second spaceron a sidewall of the second stack, a third spacer on a sidewall of thethird stack, and a fourth spacer on a sidewall of the fourth stack,opposing sidewalls of the first spacer and the second spacer defining afirst distance between the first spacer and the second spacer, opposingsidewalls of the third spacer and the fourth spacer defining a seconddistance between the third spacer and the fourth spacer, the firstdistance being less than the second distance; simultaneously etching theSiGe channel layer between the first spacer and the second spacer toform a first recess and the first silicon channel layer between thethird spacer and the fourth spacer to form a second recess, wherein theSiGe channel layer is etched at a greater vertical etching rate and at agreater lateral etching rate than the first silicon channel layer, thefirst recess having a greater depth than the second recess, the firstrecess extending laterally a greater distance under the first spacerthan the second recess extends laterally under the third spacer; andepitaxially growing a first epitaxial source/drain region in the firstrecess and a second source/drain region in the second recess.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A device comprising: a first n-type transistorcomprising: a first fin, the first fin comprising a first material on afirst dielectric material on a substrate, a first epitaxial source/drainregion and a second epitaxial source/drain region each in a respectivefirst recess in the first fin, the first fin being disposed between thefirst epitaxial source/drain region and the second epitaxialsource/drain region, and a first gate stack on the first fin; and asecond n-type transistor comprising: a second fin, the second fincomprising a second material over a first on the substrate, a thirdepitaxial source/drain region and a fourth epitaxial source/drain regioneach in a respective second recess in the second fin, the second finbeing disposed between the third epitaxial source/drain region and thefourth epitaxial source/drain region, and a second gate stack on thesecond fin.
 2. The device of claim 1, wherein the first material and thesecond material are a same material.
 3. The device of claim 1, whereinthe first material and the second material are both silicon.
 4. Thedevice of claim 1, wherein a depth of the second recess is greater thana depth of the first recess.
 5. The device of claim 1, wherein a widthof each respective second recess at a top surface of the second fin isgreater than a width of each respective first recess at a top surface ofthe first fin.
 6. The device of claim 1, wherein the first n-typetransistor is in a core logic region of the substrate, and the secondn-type transistor is in an input/output region of the substrate.
 7. Thedevice of claim 1, wherein each of the first epitaxial source/drainregion and the second epitaxial source/drain region do not completelyfill the respective first recesses, and wherein each of the thirdepitaxial source/drain region and the fourth epitaxial source/drainregion at least completely fill the respective second recesses.
 8. Thedevice of claim 1, wherein each of the first epitaxial source/drainregion and the second epitaxial source/drain region has a firstproximity distance, the first proximity distance being between a nearestsurface of the respective first epitaxial source/drain region and thesecond epitaxial source/drain region to the first gate stack and a planeof a respective nearest sidewall of the first gate stack, and whereineach of the third epitaxial source/drain region and the fourth epitaxialsource/drain region has a second proximity distance, the secondproximity distance being between a nearest surface of the respectivethird epitaxial source/drain region and the fourth epitaxialsource/drain region to the second gate stack and a plane of a respectivenearest sidewall of the second gate stack, the first proximity distancebeing the same as the second proximity distance.
 9. The device of claim1 further comprising: a first p-type transistor comprising: a third fin,the third fin comprising a third material on the substrate, a fifthepitaxial source/drain region and a sixth epitaxial source/drain regioneach in a respective third recess in the third material, the thirdmaterial being a different material from the second material, the thirdfin being disposed between the first epitaxial source/drain region andthe second epitaxial source/drain region, and a third gate stack on thethird fin; and a second p-type transistor comprising: a fourth fin, thefourth fin comprising a fourth material on the substrate, the fourthmaterial being a different material from the third material, a seventhepitaxial source/drain region and a eighth epitaxial source/drain regioneach in a respective fourth recess in the fourth material, the fourthfin being disposed between the seventh epitaxial source/drain region andthe eighth epitaxial source/drain region, and a fourth gate stack on thefourth fin.
 10. The device of claim 9, wherein the fourth material is asame a material as the second material.
 11. The device of claim 9,wherein a depth of the third recess is greater than a depth of thefourth recess.
 12. The device of claim 9, wherein a width of eachrespective fourth recess at a top surface of the fourth fin is greaterthan a width of each respective third recess at a top surface of thethird fin.
 13. A method comprising: forming a first fin on a substrate,the first fin comprising a first crystalline material on the substrate;forming a second fin on the substrate, the second fin comprising asecond crystalline material on the substrate, a material of the firstcrystalline material being different from a material of the secondcrystalline material; forming a first structure on the first crystallinematerial of the first fin and a second structure on the secondcrystalline material of the second fin; forming a first spacer along asidewall of the first structure and a second spacer along a sidewall ofthe second structure; simultaneously etching the first crystallinematerial to form a first recess in the first fin and adjacent the firstspacer, and etching the second crystalline material to form a secondrecess in the second fin and adjacent the second spacer, a width of thefirst recess at a top surface of the first fin is less than a width ofthe second recess at a top surface of the second fin, a depth of thefirst recess is greater than a depth of the second recess; andepitaxially growing a first epitaxial source/drain region in the firstrecess and a second source/drain region in the second recess.
 14. Themethod of claim 13, wherein the first recess extends laterally under thefirst spacer further than the second recess laterally extends under thesecond spacer.
 15. The method of claim 13, wherein the first crystallinematerial is silicon-germanium, and the second crystalline material issilicon.
 16. The method of claim 13, wherein the simultaneously etchingincludes etching the first crystalline material at a first verticaletching rate and etching the second crystalline material at a secondvertical etching rate, the first vertical etching rate being greaterthan the second vertical etching rate.
 17. The method of claim 13,wherein the simultaneously etching includes etching the firstcrystalline material at a first lateral etching rate and etching thesecond crystalline material at a second lateral etching rate, the firstlateral etching rate being greater than the second lateral etching rate.18. A method comprising: forming a first fin in an n-type core logicregion of a substrate, the first fin comprising a first crystallinematerial and a dielectric material, the dielectric material being on thesubstrate, the first crystalline material being on the dielectricmaterial; forming a second fin in an n-type input/output (I/O) regionthe substrate, the second fin comprising a second crystalline materialon the substrate, materials of the first crystalline material and thesecond crystalline material a same material; forming a first gatestructure on the first fin and a second gate structure on the secondfin; forming a first spacer along a sidewall of the first gate structureand a second spacer along a sidewall of the second gate structure;simultaneously etching the first fin to form a first recess in the firstfin and a second recess in the second fin, the first recess beingadjacent the first spacer and the second recess being adjacent thesecond spacer, the second recess having a greater depth than the firstrecess, the first recess and the second recess extending laterally asame distance under the first spacer and the second spacer,respectively; and epitaxially growing a first source/drain region in thefirst recess and a second source/drain region in the second recess. 19.The method of claim 18, wherein the second crystalline material isetched at a greater vertical etching rate than the first crystallinematerial, and the second crystalline material is etched at a samelateral etching rate as the first crystalline material.
 20. The methodof claim 18, wherein the first crystalline material and the secondcrystalline material are silicon.